On 2016-02-22 14:11:05 +0100, Fabien COELHO wrote: > > >I did a quick & small test with random updates on 16 tables with > >checkpoint_flush_after=16 checkpoint_timeout=30 > > Another run with more "normal" settings and over 1000 seconds, so less > "quick & small" that the previous one. > > checkpoint_flush_after = 16 > checkpoint_timeout = 5min # default > shared_buffers = 2GB # 1/8 of available memory > > Random updates on 16 tables which total to 1.1GB of data, so this is in > buffer, no significant "read" traffic. > > (1) with 16 tablespaces (1 per table) on 1 disk : 680.0 tps > per second avg, stddev [ min q1 median d3 max ] <=300tps > 679.6 ± 750.4 [0.0, 317.0, 371.0, 438.5, 2724.0] 19.5% > > (2) with 1 tablespace on 1 disk : 956.0 tps > per second avg, stddev [ min q1 median d3 max ] <=300tps > 956.2 ± 796.5 [3.0, 488.0, 583.0, 742.0, 2774.0] 2.1%
Interesting. That doesn't reflect my own tests, even on rotating media, at all. I wonder if it's related to: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=23d0127096cb91cb6d354bdc71bd88a7bae3a1d5 If you use your 12.04 kernel, that'd not be fixed. Which might be a reason to do it as you suggest. Could you share the exact details of that workload? Greetings, Andres Freund -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
